Many commercial power consumers, such as hospitals and computer facilities require continuous backup electrical power. Existing systems use a UPS, consisting of a converter for changing commercial alternating current (AC) power to DC power. The output of the converter is coupled to a DC bus to which is also coupled battery backup power. Finally, the DC bus is coupled at its output to an inverter for converting DC into AC. The AC output of the UPS supplies a primary load, and if the commercial power fails, even momentarily, the batteries support the primary load until an emergency generator can be staffed and coupled to the primary load. Thus, seamless compensation for a failure of commercial power is provided.
Batteries are expensive to purchase and maintain, and create significant environmental challenges and expenses upon disposal. Some modern systems use flywheel generators for providing temporary DC power in place of batteries. Some flywheels are made of steel and require about 3000 watts to operate in a steady state. These steel flywheels typically have recovery times substantially longer than their power production periods, making them unresponsive to repeated interruptions and variations in input power.
Current power systems, which seek to integrate various renewable-energy sources of power such as, without limitation, solar photovoltaic (PV), wind, geothermal, bio-diesel generators, and hydro systems, require significant infrastructure for connectivity and power conditioning. In renewable energy power systems that seek to exploit multiple sources of renewable energy, the costs can be commercially prohibitive. Typically, each separate renewable energy power source has it own infrastructure for producing AC current and synchronizing the phase or phases with the AC power line current. Even with systems using only a few sources, the significant infrastructure requirements impose undesirable initial costs and maintenance costs. Accordingly, what is needed are renewable energy power systems with reduced infrastructure, higher capacity for handling a variety of loads and sources, and which can be easily integrated into commercial power systems.
Modern hydrogen gas production systems based on electrolyzers are stand-alone systems with both high-pressure and low-pressure storage tanks. While a significant amount of energy is required to compress the hydrogen gas for storage, much of that energy is wasted because the storage pressure is much higher than many (but not all) end-user pressure tanks. For example, a hydrogen production facility may store hydrogen at approximately 7000 psi while hydrogen-fueled vehicles may store hydrogen at 4500 psi.
The 2500 psi difference is much more than is needed to overcome conduit losses. Accordingly, what is needed are hydrogen gas production systems that are integrated with electrical renewable energy power systems and which permit recovery of some of the otherwise wasted pressure differential pressure energy in the stored hydrogen gas.
To meet the above-mentioned needs and to solve the above-mentioned problems, applicants present what follows.